[Lustre-discuss] Implementing MMP correctly

[Michael Schwartzkopff]

Hi,

I am trying to understand howto implement MMP correctly into a lustre failover 
cluster.

As far as I understood the MMP protects the same filesystem beeing mounted by 
different nodes (OSS) of a failover cluster. So far so good.

If a node was shut down uncleanly it still will occupy its filesystems by MMP 
and thus preventing the clean failover to an other node. Now I want to 
implement a clean failover into the Filesystem Resource Agent of pacemaker. Is 
there a good way to solve the problem with MMP? Possible sotutions are:

- Disable the MMP feature in a cluster at all, since the resource manager 
takes care that the same resource is only mounted once in the cluster

- Do a "tunefs -O ^mmp <device>" and a "tunefs -O mmp <device>" before every 
mounting of a resource?

- Do a "sleep 10" before mounting a resource? But the manual says "the file 
system mount require additional time if the file system was not cleanly 
unmounted."

- Check if the file system is in use by another OSS through MMP and wait a 
litte bit longer? How do I do this?

Please mail me any ideas. Thanks.

-- 
Dr. Michael Schwartzkopff
MultiNET Services GmbH
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